[Live-devel] RTSP video decoding - packets too small

[Guillaume Ferry]

Le 07/09/2010 08:47, Ross Finlayson a écrit :
>> This video has (on purpose) no audio track, so I can focus on video 
>> stream only.
>> Payload of value 32 is an MPEG1 or MPEG2 video
>
> That's correct.
>
> An important thing to note about the RTP payload format for MPEG-1 or 
> MPEG-2 video (defined in RFC 2250) is that the data units delivered by 
> RTP are not (necessarily) complete video frames (even though our code 
> refers to them as 'frames' - which is admittedly a bit confusing).  
> For MPEG-1 or 2 video, the data units delivered by RTP - i.e., 
> delivered one-at-a-time by a "MPEG1or2VideoRTPSource" object - can be 
> MPEG headers, or one or more video 'slices', but need not be a 
> complete video frame.  (See RFC 2250 section 3.1 and Appendix 1.) This 
> allows a decoder to handle data loss without necessarily discarding an 
> entire video frame, but also means that it has to be a little smarter 
> about properly detecting when it has received enough data to make up 
> an entire frame.
Yes, and I have been confused by the frame naming, especially since it 
worked just fine with audio files !
I'll dive a little deeper into libav* code, I think my solution lies by 
there :)

Thanks for your help Ross.

Best regards,
Guillaume.

PS : by the way, thanks for the asynchronous API, it was really a key 
feature I missed.

-- 
Guillaume FERRY
Bertin Technologies
Département Bertin Conseil
Activité Traitement de l'Information et du Contenu
/Tél/ 	01.39.30.62.09
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/Mail/ 	ferry at bertin.fr
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